1. Field of the Invention
The present invention relates to water-based paint booth flood sheet solutions, and more specifically to water-based paint booth flood sheet solutions with an aprotic heterocyclic oxygenate, an alkyl aryl glycol monoalkyl ether and a surfactant.
2. Description of the Prior Art
It has been taught that various compounds materials can be used, in place of water, as atomized paint particle knock-down media in large industrial paint spray booths.
The air in the paint spray booth that contains these paint overspray particles is pulled through grating in the bottom of the booth into and through a "curtain" or flood sheet of fluid that traps some of the paint particles as an initial step in purification clearing of the air prior to allowing the air to pass out through an exhaust stack into the outside environment.
In general, water has been used as the medium in the large (100,000-200,000 gallons) flood sheet systems. However, U.S. Pat. No. 4,339,248 teaches the use of a water insoluble, high boiling plasticizer type of material as the paint catching medium. The use of a long chain of polyether, as the paint catching medium is disclosed in U.S. Pat. 4,102,303. In addition, U.S. Pat. No. 4,919,691 teaches the use of a high boiling oil and dibasic ester, and water emulsion as a flood sheet composition.
The prior art attempted to improve over the use of water at cleaning paint particles out of the air stream that passed through it. However, in all cases, the materials used were high boiling materials.
However, these methods do not work in the reclamation of uncured paint resin. The inclusion of these high boiling materials, which do not evaporate even at the temperatures that the paints normally crosslinked, does not work. The paint left in the "high boiling" sludge, after a distillation process, cannot be cured into a paint film. The result is cured chunks of paint floating in pools of the high boiling compounds.
Rather than the expensive process of continually disposing of the high boiling paint catching compounds, once they had reached a paint saturation point, it has been known to include detackifying compounds to chemically cure the paint into hard powder particles which float to the surface of the paint catching medium and can then be easily separated. The detackified or chemically cured paint particles are no longer capable of being recycled and used as a paint. They are fully cured resin particles that are waste and require disposal.
A further improvement over the use of these high boiling water insoluble compounds as the paint catching media, is disclosed in U.S. Ser. No. 07/445,314, herein incorporated by reference. A lower boiling water based solution of, for example, N-methyl pyrrolidone, tripropylene glycol mono methyl ether, di basic ester, and water is used. This type of water based solution allows the paint to be caught and solvated, without the inclusion of a detackifying agent. The paint resin is then easily recovered, via a distillation process at temperatures lower than those at which the paints cure, giving rise to a final product that is not disposed of as waste, but is in a form that can be re-used as a film forming paint.
In view of the current environmental and regulatory climate, it is important to further reduce volatile organic emissions in the flood sheet spray booth. A large amount of agitation is associated with the keeping of the flood sheet fluid in continual motion. This causes an increase in the amount of volatile organic emissions being given off by the flood sheet fluid.
Therefore, in spite of these disclosures, there is a need for a water-based flood sheet solution that would trap paint overspray particles, without the inclusion of a detackifying agent, and at the same time have a lower volatile organic emissions.